The present invention relates to a process for preparing a cosmetic formulation and to a cosmetic formulation composition. More particularly, the present invention relates to a process for preparing a cosmetic formulation and to a cosmetic formulation composition utilizing a high internal phase ratio (HIPR) emollient-in-water emulsion, for example, wherein the emollient of the emulsion may be a silicone elastomer or a suncreen agent.
Historically, cosmetic formulations have been prepared by emulsifying an oil phase with an aqueous phase matrix using a batch process, wherein the oil and water mixture is sheared in a large vessel. The oil phase, typically, includes a mixture of complex and varying oil-miscible ingredients and, consequently, batch-to-batch reproducibility of oil droplet size is often elusive. Moreover, processing time can be quite long and scale-up of the process from the benchtop to the manufacturing plant can be frustrating because tank-based processes often do not scale up in a linear fashion.
In WO 01/54663, Wilmott et al. disclose a possible solution to the problems associated with formulating personal care products by providing a substantially surfactant-free stable aqueous dispersion (that is, stable for at least two months), containing up to 70%, more preferably up to 50%, by weight of an oil phase, to which active ingredients can be added. This approach allows simple mixing of all ingredients, without the need for sub-phases or any special processing, to create a formulated cosmetic product. Nevertheless, there still remains an ever-increasing need to offer formulators more flexibility in controlling and fine tuning the properties of the final product, and to allow the formulators to use dispersions at their convenience.
For example, although there are various known processes for making sunscreens, there is still a need to make an unencapsulated sunscreen agent emulsion with an improved sun protection factor (SPF).
Organic sunscreen emulsions with a particle size of less than 2 microns are known in the art wherein the organic sunscreen is encapsulated and the effective sun protection factor is improved with respect to conventional formulations (Duncan Aust, “Sunscreen SPF Enhanced By Nano-Dispersion Technology Study,” Rose Sheet, Jun. 4, 2001). Unencapsulated organic sunscreens of small size are known by templating on solid disperse polymers (U.S. Pat. No. 6,216,948) or Pickering emulsions (U.S. Patent Publication No. 20020160030). Dispersions of solid organic sunscreens less than 2 microns have been made by grinding (micronizing) the solid sunscreen (U.S. Pat. No. 5,980,872). The use of an effective amount of a surfactant for making unencapsulated organic sunscreen emulsions less than 2 microns is not known.
As one objective of the present invention, it would be desirable to make unencapsulated organic sunscreen agents emulsions with emulsifying surfactants and a particle size less than 2 microns, preferably with improved SPF and critical wavelength.